Book about a boy who can shapeshift; he joined a circus after loosing a finger

Question

I recall bits from one of my dad's books that I read in the late 1980’s.

It was about a boy who lost his thumb (or finger) when a door was shut on it. He joined a circus or carnival where he looked like a woman that was in an act in the carnival. The man that ran the circus/carnival asked to look at the boy's thumb and it had grown back.

I recall the man talking about a pair of trees: when he carved something in one of the trees, the other tree would have the same carving.

In the end, I recall the boy could control how he looked, like shape-shifting.

I’ve been searching for this book forever but cannot seem to find it. I asked my dad and he thought it might be a JRR Tolkien book, but I don’t think so.

Answer 1

The Dreaming Jewels (aka The Synthetic Man, 1950) by Theodore Sturgeon, his first novel. 8 year old Horty Bluett loses some fingers when his adoptive father slams a door on his hand. He runs away to join a circus. He masquerades as a female dwarf. Vaguely remember the bit about the trees. Jewel-like aliens can create flawed or perfect copies of living beings or objects.